Oct. I, 1920 



Fusarium-B light (Scab) of Wheat and Other Cereals 



dies as a result of infection from the kernel. In many cases, however, 

 the seedling survives the attack and reaches full development. 



Kernels of rye from blighted heads show symptoms similar to those 

 described for wheat. The kernels which are directly attacked by the 

 fungus in blighted barley heads become dirty brown in color and are 

 lighter in weight than the normal kernels if the infection takes place at an 

 early stage in development. Often barley kernels are found with salmon- 

 colored spots on which there are masses of conidia of Fusarium. Oat 

 kernels show much the same symptoms as barley, except that they remain 

 lighter in color. In all these cereals, symptoms similar to those caused 

 by Fusarium-blight may be caused by other agencies, such as the 

 exposure of the grain to rain. 



SEEDLING-BLIGHT 



Seedlings from seed naturally or artificially infected with Gibberella 

 saubinetii are subject to attacks by this organism at a very early stage of 

 their development, and the visible symptoms of the infection may 

 become evident at the time of the germination of the seed or only a few 

 days later. The first symptoms appear on the young coleorhiza and 

 coleoptile and consist of the browning and rotting of these parts. The 

 coleorhiza and coleoptile, which always die shortly after the formation 

 of the permanent roots and the appearance of the first foliage leaf, seem 

 to offer a good medium for the establishment of the various species of 

 Fusarium, which then penetrate into the tissues of the permanent roots 

 and the first foliage leaf, causing the browning and rotting of the invaded 

 portions. If the attack has proceeded successfully, the formation of 

 the two lateral roots, in the case of wheat, is either prevented or these 

 roots are destroyed before attaining any considerable size. The older 

 or basal portions of the roots are sometimes pink in color, but they are 

 usually brown to black. The lower portions of the roots continue normal 

 and healthy until their food supply is cut off by rotting of the upper parts. 

 Often the remnants of the kernel are heavily overgrown with the myce- 

 lium of the fungus, and in some cases they attain a dark carmine red 

 color. The leaves above the infected portion, which seldom extends 

 above the ground if the plant is still very small, become yellow and later 

 brown, the discoloration beginning at the tips. If the leaves are over 

 6 cm. long they usually take on a light-green color and then collapse and 

 wilt very rapidly, showing a blighted effect. In many cases the infection 

 may be restricted to the primary roots, the coleorhiza and coleoptile, 

 and even to the first foliage leaf. In such cases new roots are soon 

 formed, the second and third leaves develop, and the plant may recover 

 almost entirely from the attack, which is still restricted to the parts 

 originally infected. Such plants, if examined three or four weeks later, 

 will show no symptoms of the infection and will usually continue to 

 develop normally. 



